Color corrected images for projectors

ABSTRACT

In example implementations, an apparatus includes a camera, an image signal processor and a display processor. The camera measures metered values of an image projected onto a surface. The image signal processor is in communication with the camera to receive the metered values of the image on the surface. Display parameters are calculated by the image signal processor based on the metered values of the image on the surface that is measured. The display processor is in communication with the image signal processor and a projector. The display processor generates a color corrected image projected onto the surface by the projector. The color corrected image is generated based on the display parameters.

BACKGROUND

Projectors are a popular way to replicate large theater screens for homeentertainment or for generating a large display for a meeting.Projectors can be used to generate an image from a media source onto awall or screen. A projector is generally a pass-through device. In otherwords, the projector simply receives image data and outputs the imagedata onto the wall or screen that is received without modification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example system of the presentdisclosure;

FIG. 2 is an example of an apparatus of the present disclosure;

FIG. 3 is another example of an apparatus of the present disclosure; and

FIG. 4 is a flow diagram of an example method for generating a colorcorrected image for a projector.

DETAILED DESCRIPTION

The present disclosure provides example systems and methods forgenerating color corrected images for projection systems. For example,currently a projector simply displays whatever image is provided to theprojector by a media source. A projector typically projects an imageonto a white surface. However, a white surface may not be available andthe surface may be another color. Typically, the user may not know howto adjust the display parameters of the projector, or the media source,to adjust the projected image to improve the projected image that isdisplayed onto a non-white colored surface.

In addition, a user can manually set various parameters such asbrightness when the image is initially projected. However, over time thelighting conditions may change within the room that the user is watchingthe projected image. For example, the user may begin viewing theprojected image during the day, but over the course of a few hours thesun may set and the room may become dark. In another example, the usermay begin viewing the projected image with the shades open on a sunnyday, but then the shades may be closed while viewing the projectedimage. In another example, the user may begin viewing the projectedimage in the dark, but then someone may turn on lights in the room, andso forth.

Another factor that can affect a user's viewing experience is the typeof image content. For example, different types of images may havedifferent optimizations. For example, the amount of adjustment requiredto display a bar chart, a solid color or text on a non-white coloredsurface may be different from a face, cinematic movie, and so forth.

Yet another factor that can affect a user's viewing experience may beuser preferences. For example, some users may prefer brighter imageswith less contrast, while other users may want more contrast with areduction in average brightness.

Examples of the present disclosure measure metered values of theprojected image on the surface and the environment and generate a colorcorrected image based on the measured metered values. The measurementsmay be taken continuously and the color corrected image may becontinuously, or periodically, generated. In addition, the type of imageand the user preferences may be taken into account when adjusting theprojected image based on the measured metered values. Thus, a user'sviewing experience may be maximized irrespective of a color of thesurface that the image is projected onto.

FIG. 1 illustrates an example system 100 of the present disclosure. Thesystem 100 may include a media hub 102, a projector 106 and a surface110. In one example, the surface 110 may be a wall, a screen, and thelike. In one example, the surface 110 may be a colored wall. In otherwords, the surface 110 is a non-white colored wall (e.g., an off-whitecolor, tan, beige, yellow, red, green, blue, and the like). In anotherexample, the surface 110 may be a heterogeneous surface. In other words,the surface 110 may have different colors and textures (e.g., when thesurface 110 is a bulletin board).

When the surface 110 is a colored wall or a heterogeneous surface, theprojected image may not appear correctly to the user. For example, mostimages or videos are generated based on an assumption that the imagewill be projected onto a white wall or a white screen. However, whenimages or videos are projected onto a colored wall, the color of thewall may cause the characteristics of the image or video to change.Thus, the image or video may not appear correctly to the user (e.g.,contrast may be off, colors may appear incorrectly, and the like).

The media hub 102 may be any media generating device (e.g., a Blu-raydisc player, a digital media player, a video game console, a computer,and the like). The media hub 102 may be a source of the images or videosthat are displayed by the projector 106. The media hub 102 may transmitimages to be projected to the projector 106 via a wired or wirelessconnection. For example, the media hub 102 may be connected via a highdefinition media interface (HDMI) cable, a universal serial bus (USB)cable, a digital video interface (DVI) cable, a wireless fidelity(Wi-Fi) connection, a Bluetooth connection, and the like.

In one implementation, the media hub 102 may be inside, or be part of,the projector 106. In other words, the media hub 102 and the projector106 may be combined as a single device. As a result, the media huh 102and the projector 106 may be connected via internally wired connectionsor an internal communication bus.

In one example, the media hub 102 may measure metered values of thesurface 110 and the environment (e.g., a room that the media hub 102 andthe projector 106 are located). For example, when the surface 110 is acolored wall, the metered values of the image on the colored wall may bemeasured so that the image can be corrected to compensate for thecolored wall. For example, a white color on a tan colored wall mayappear to have an off-white color, a gain level may appear to be higherwhen the video is projected onto a dark colored wall, and the like.

In addition, as the image or the video is playing and being projectedonto the surface 110, the lighting conditions in the environment maychange. Changes to the lighting conditions can further exacerbatedistortions to the image or video characteristics when projected onto acolored wall.

In one example, the media hub 102 may use a local camera (e.g. a cameraattached to the device as shown in FIG. 2 below) or a remote camera 104.Although a single remote camera 104 is illustrated, it should be notedthat any number of remote cameras 104 may be deployed.

In one implementation, different remote cameras 104 may be dedicated todifferent measurements. For example, a first remote camera 104 may lookat projected light pixel by pixel or region by region, a second remotecamera 104 may measure when the image is not projected to get a baselinefrom the surface 110, and so forth.

The measured metered values may be processed by the media hub 102 togenerate a color corrected image 108. The color corrected image 108 maybe transmitted to the projector 106 and projected onto the surface 110.In some implementations, the media hub 102 may adjust display settingsto generate the color corrected image 108. For example, the media hub102 may adjust the display settings over the wired or wirelessconnection to the projector 106. Alternatively, the display settings maybe transmitted to the projector 106 with the color corrected image andthe projector 106 may adjust display settings based on the displayparameter adjustments that are received from the media hub 102.

In some implementations, when the surface 110 is a heterogeneoussurface, the media hub 102 may generate localized color corrected images108. In other words, the measured metered values may be different fordifferent portions of the heterogeneous surface. As a result, the colorcorrected image 108 may be different for different areas of the colorcorrected image 108 depending on where the color corrected image 108 isprojected onto the heterogeneous surface.

In some implementations, the light source could be a single lightsource. In other implementations, there may be multiple light sourcesand the surface 110 may be illuminated with mixed light sources. Forexample, some light sources may be a natural light source from an openwindow and other light sources may be from a light bulb, or otherartificial light source.

FIG. 2 illustrates a block diagram of an example media hub 102. Themedia hub 102 may include a camera 202, an image signal processor 204and a display processor 206. In one example, the image signal processor204 may also be referred to as a compute, analyze and generateoptimizations processor. In one example, the display processor 206 mayalso be referred to as an in-line real-time video processor. Althoughthe image signal processor 204 and the display processor 206 areillustrated as separate processors in FIG. 2, it should be noted thatthe image signal processor 204 and the display processor 206 may bedeployed as a single processor within a system on a chip (SOC).

In one example, the camera 202 may include a complementary metal oxidesemiconductor (CMOS) sensor that is used to meter the light and tocapture the images that are projected onto the surface 110. The camera202 may capture the video and may measure the metered values of an imageprojected onto the surface 110 and the lighting within the room. Asdiscussed, in some examples the camera 202 may measure the meteredvalues of the image projected onto different areas of the surface 110for a heterogeneous surface.

The measured metered values may include a luminance value, a chrominancevalue, or any other color or light parameter that can be measured. Themeasured metered values may be recorded as part of an image frame data.These values may be read by the image signal processor 204. The imagesignal processor 204 may extract the measured metered values and expressthem to an intelligent software (SW) system (not shown). For example,the intelligent SW system may see a clear glass of water under a redlight. In such an example, the output of the red cast is removed makingthe rendering seem natural. As a result, the intelligent SW system whenpresented with a clear glass with red wine under day light may notconfuse the red wine for red light and renders the image without change.

The intelligent SW system may be a camera white balance software thatcan be modified for the present disclosure. For example, the intelligentSW system may be modified to understand color walls similar to theexample of the glass of water and red wine described above to makeproper decisions.

In one implementation, the intelligent SW system may process themeasured metered values and output information that is fed back to theimage signal processor 204. With the information from the intelligent SWsystem, the image signal processor 204 may proceed with subsequentprocessing stages including color correction and color space conversion.With the information from the intelligent SW system, the media hub 102may generate the color corrected images and a projector displayparameters control signal to compensate for the variances of themeasured metered values from the surface 110.

In one example, the camera 202 may sample every frame of the video imagethat is captured. In other words, the camera 202 may continuouslycapture a video image that is being projected by the projector 106 ontothe surface 110 and meter the light of each frame of the video imagethat is captured.

The measured metered values may then be fed to the image signalprocessor 204 as an input 203. In some implementations, the image signalprocessor 204 may also receive the measured metered values from theremote camera 104. The measured metered values may then be averaged forcalculating the display parameters, as discussed below. The image signalprocessor 204 may be a discrete processor or a built-in processor (e.g.,part of the main processor of the media hub 102). In one example, theimage signal processor 204 may be deployed as an application specificintegrated circuit (ASIC) chip.

The image signal processor 204 may convert the measured metered valuesinto display parameters. The display parameters may include a whitebalance, a gain, an exposure level, and like. In other words, the imagesignal processor 204 may use the measured metered values to calculatethe display parameters.

In one implementation, the image signal processor 204 may also receivean input 208 of a video image that is being projected and an input 210of user preferences. The image signal processor 204 may use the input208 of the video image to determine a type of video image that is beingprojected. As described above, the type of video image may affect thevalues of the display parameters determined by the image signalprocessor 204.

In addition, the image signal processor 204 may use the input 210 of theuser preferences to further adjust the display parameters. For example,the user preferences may divert from the display parameters determinedby the image signal processor 204. For example, the image signalprocessor 204 may alter a white balance based on the input 203 of themeasured metered values, but may further alter the white balance to meeta desired level of brightness, contrast, saturation, color balance, andthe like, specified in the user preferences.

It should be noted that adjusting the display parameters based on theinput 208 of the video image and the input 210 of the user preferencesmay be an example implementation. In other words, in otherimplementations, the image signal processor 204 may convert the input203 of the measured metered values into the display parameters withoutusing the input 208 of the video image or the input 210 of the userpreferences. However, any combination of the input 203 of the measuredmetered values, the input 208 of the video image and the input 210 ofthe user preferences may be used to determine the display parameters.

In one example, if the projector 106 has display settings, the imagesignal processor 204 may send a projector display parameters controlsignal as an output 212. The output 212 may control various displaysettings of the projector 106 to display the color corrected image 108.For example, the output 212 may be provided in addition to the colorcorrected image 108 generated by the display processor 206, as describedbelow.

The display parameters may be sent to the display processor 206. Thedisplay processor 206 may be an image display processor for the mediahub 102 that generates the color corrected image based on the displayparameters calculated by the image signal processor 204. For example,the display processor 206 may compare the display parameters toreference display parameters. For example, the media hub 102 may includereference display parameters for how an image should appear (e.g., apreferred white level, a preferred gain level, a preferred exposurelevel, a preferred contrast, a preferred brightness, and the like). Thereference display parameters may be pre-defined based on an industrystandard or may be user-defined (e.g., a user may establish his or herpreferences during an initial set-up process of the media hub 102).

In one example, each display parameter may be compared to a respectivereference display parameter to calculate a delta. If the delta isgreater than a predefined threshold for a particular display parametercompared to a respective reference display parameter, then the displayprocessor 206 may adjust at least one display setting to adjust aparticular display parameter for the image such that the delta is withinthe predefined threshold. Each display parameter may be compared to therespective reference display parameter and adjusted if the delta isgreater than the predefined threshold to generate the color correctedimage 108.

For example, an image or a video projected onto a surface 110 that iswhite may be expected to have a particular white balance and aparticular gain. However, when the image or the video is projected ontoa surface 110 that is a non-white colored wall, the white balance andthe gain for the projected image or video may be distorted. Thus, thedisplay parameters calculated by the image signal processor 204 may beout of range of what the display parameters are expected to be had theimage been projected onto a white colored wall. The comparisons maydetermine an amount of distortion of the display parameters and adjustthe display settings to bring the display parameters close to thereference display parameters.

The predefined threshold may be an absolute value. In other words, theadjustment may be made based on whether the particular display parameteris less than the respective reference display parameter or greater thanthe respective display parameter.

In some examples, the display setting may be directly correlated to thedisplay parameter. For example, the media hub 102 or the projector 106may have a gain setting to adjust the gain to the calculated gain. Inanother example, the display setting may not be directly correlated tothe display parameter. For example, there may be separate red, green andblue settings to adjust a white balance to the calculated white balance.

In one implementation, the display processor 206 may continuouslygenerate the color corrected image 108. In other words, the displayprocessor 206 may also continuously generate the color corrected image108 based on the display parameters received from the image signalprocessor 204. In another implementation, the display processor 206 maygenerate the color corrected image 108 for a predefined number of frames(e.g., every 500 frames, every 1000 frames, and the like).

In one implementation, the display processor 206 may also receive theinput 208 of the video image. The display processor 206 may generate thecolor corrected image 108 by applying the display parameters to theinput 208 of the video image. The color corrected image 108 may then betransmitted to the projector 106 as an output 214.

In another example, the display processor 206 may adjust the video imagereceived via the input 208. For example, the display parameters may beapplied to the video image by adjusting the video image directly. Forexample, the gamma on an R channel of the video image may be adjusted bythe display processor 206. The color corrected image 108 may then betransmitted to the projector 106 as the output 214.

It should be noted that both the display settings may be adjusted tobring the display parameters within the threshold value of the referencedisplay parameters, the video image can be directly adjusted or bothadjustments can be made. In one example, when both adjustments areimplemented the adjustment to the display parameters may be sent as aseparate output 212 to the projector 106 from the color corrected imagethat is sent as the output 214 to the projector 106. In otherimplementations, the display parameter adjustments and the directadjustments to the video image may be multiplexed together as a singleoutput 214 that is sent to the projector 106.

In one implementation, the image signal processor 204 and the displayprocessor 206 may be modified to work together. For example, the imagesignal processor 204 and the display processor 206 are not usuallylocated within the same device. As a result, the image signal processor204 and the display processor 206 may have different gamma curves forcorrecting images. However, the present disclosure may adjust the gammacurves to be the same for the image signal processor 204 and the displayprocessor 206. In other words, the image signal processor 204 and thedisplay processor 206 use a single unified gamma curve instead of twoseparate gamma curves that could be slightly different from one another.

In addition, the gamma curve used for the image signal processor 204 andthe display processor 206 may be modified to be specific for indoor use.In contrast, image signal processors 204 are typically found in pointand shoot cameras that are used indoors and outdoors. Thus, the gammacurves for point and shoot cameras reflect image corrections for bothindoor and outdoor lighting conditions.

FIG. 3 illustrates an example of an apparatus 300. In one example, theapparatus may be the image signal processor 204. In one example, theapparatus 300 may include a processor 302 and a non-transitory computerreadable storage medium 304. The non-transitory computer readablestorage medium 304 may include instructions 306, 308 and 310 that whenexecuted by the processor 302, cause the processor 302 to performvarious functions.

In one example, the instructions 306 may include instructions to receivemetered values of an image projected onto a surface from a camera. Theinstructions 308 may include instructions to calculate a displayparameter based on the metered values of the image on the surface thatis measured. The instructions 310 may include instructions to transmitthe display parameter to a display processor to generate a colorcorrected image based on the display parameter, wherein the colorcorrected image is transmitted to a projector to display the colorcorrected image onto the surface. In one example, the display parametermay be a projector display parameters control signal that is sentdirectly to the projector.

FIG. 4 illustrates a flow diagram of an example method 400 forgenerating a color corrected image for a projector. In one example, theblocks of the method 400 may be performed by the media hub 102 or thedisplay processor 206.

At block 402, the method 400 begins. At block 404, the method 400receives a display parameter of an image projected onto a surfacecalculated by an image signal processor based on metered values of theimage on the surface that is measured by a camera. For example, a cameraof the media hub, or remote cameras in communication with the media hub,can capture video images and provide measured meter values to an imagesignal processor. The measured metered values may include luminancevalues, chrominance values, and the like.

The image signal processor may calculate display parameters based on themeasured meter values. The display parameters may include a whitebalance, a gain, an exposure level, a contrast, and the like. The imagesignal processor may adjust the display parameters based on a comparisonof the display parameters to respective reference display parameters.The display parameters (whether adjusted or not) may then be sent to thedisplay processor.

In some implementations, the image signal processor may calculate thedisplay parameters based on additional factors. For example, the userpreferences, the type of video image that is being projected, and thelike, may be taken into account when calculating the display parameters.

At block 406, the method 400 generates a color corrected image based onthe display parameters. When the image is projected onto a surface thatis a non-white color, the display parameters of the image may bedistorted. For example, the image may appear to be dull on a tan coloredwall, or white images may have a tan hue, and the like. As a result, thedisplay parameters that are calculated from measured metered values maybe out of range of a reference display parameter based on the imageprojected onto a white colored surface.

As a result, the delta between the display parameter and a referencedisplay parameter may be calculated. If the delta is greater than athreshold, the color corrected image may be generated. In some examples,the calculating and generating may be performed continuously. In otherexamples, the calculating and generating may be performed for apredefined number of frames of the video image captured by the camera(e.g., every 500 frames, every 1000 frames, and the like).

In one example, the color corrected image may be generated by adjustingat least one display setting. For example, a display setting may beadjusted to change the display parameter such that the delta between thedisplay parameter and the reference display parameter is within thethreshold.

In another example, the color corrected image may be generated byadjusting the video image directly. For example, a gamma may be changedon an R channel of the video image. In one implementation, the colorcorrected image may be generated by adjusting at least one displaysetting and adjusting the video image directly.

At block 408, the method 400 transmits the color corrected image to aprojector to project the color corrected image onto the surface. Forexample, the color corrected image may be transmitted over a wired orwireless connection. In some examples, the color corrected image may betransmitted with display setting changes to change display settings ofthe projector.

In some implementations, the method 400 may be continuously repeatedwhile the lighting conditions are changing and the media hub is playingthe image. In other words, the lighting conditions in the room maygradually change from lighter to darker, or vice versa, and the method400 may continuously operate to generate the color corrected image. Atblock 410, the method 400 ends.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

The invention claimed is:
 1. An apparatus, comprising: a camera tomeasure metered values of an image projected onto a surface; an imagesignal processor in communication with the camera to receive the meteredvalues of the image on the surface and to calculate display parametersbased on the metered values of the image on the surface that ismeasured; and a display processor in communication with the image signalprocessor and a projector, the display processor to generate a colorcorrected image projected onto the surface by the projector when adifference between the display parameters and reference displayparameters exceeds a threshold, wherein the color corrected image isgenerated based on the display parameters.
 2. The apparatus of claim 1,wherein the image signal processor generates a projector displayparameters control signal in addition to the color corrected image thatis generated.
 3. The apparatus of claim 1, wherein the image signalprocessor receives user preferences and a video image to determine atype of video image that is being projected.
 4. The apparatus of claim1, wherein the surface comprises a colored wall.
 5. The apparatus ofclaim 1, wherein the metered values that are measured comprise achrominance value and a luminance value.
 6. The apparatus of claim 1,wherein metered values are continuously measured in changing lightingconditions by the camera.
 7. The apparatus of claim 1, wherein the imagesignal processor and the display processor include a unified gammacurve.
 8. A method, comprising: receiving, by a processor, a displayparameter of an image projected onto a surface calculated by an imagesignal processor based on metered values of the image on the surfacethat is measured by a camera; determining, by the processor, that adifference between the display parameter and a reference displayparameter is greater than a threshold; generating, by the processor andin response to the determination, a color corrected image based on thedisplay parameter; and transmitting, by the processor, the colorcorrected image to a projector to project the color corrected image ontothe surface.
 9. The method of claim 8, wherein the color corrected imageis generated for a periodic number of frames.
 10. The method of claim 8,comprising: generating a projector display parameters control signal toadjust at least one display setting of the projector in addition to thecolor corrected image that is generated.
 11. The method of claim 8,wherein the receiving, the generating, and the transmitting areperformed continuously in changing lighting conditions while the imageis projected onto the surface.
 12. The method of claim 8, wherein thesurface comprises a colored wall.
 13. A non-transitory computer readablestorage medium encoded with instructions executable by a processor, thenon-transitory computer-readable storage medium comprising: instructionsto receive metered values of an image projected onto a surface from acamera; instructions to calculate a display parameter based on themetered values of the image on the surface that is measured; andinstructions to transmit the display parameter to a display processor togenerate a color corrected image based on the display parameter, theprocessor and the display processor having a unified gamma curve,wherein the color corrected image is transmitted to a projector todisplay the color corrected image onto the surface.
 14. Thenon-transitory computer readable storage medium of claim 13, wherein theinstructions to receive, the instructions to calculate and theinstructions to transmit are performed continuously in changing lightingconditions while the image is being projected onto the surface.